title: Effect of poly(phosphate) anions on glyceraldehyde-3-phosphate dehydrogenase structure and thermal aggregation: comparison with influence of poly(sulfoanions).
abstract: BACKGROUND
  It is well documented that poly(sulfate) and poly(sulfonate) anions suppress protein thermal aggregation much more efficiently than poly(carboxylic) anions, but as a rule, they denature protein molecules. In this work, a polymer of different nature, i.e. poly(phosphate) anion (PP) was used to elucidate the influence of phosphate groups on stability and thermal aggregation of the model enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH).
  
  
  METHODS
  Isothermal titration calorimetry and differential scanning calorimetry were used for studying the protein-polyanion interactions and the influence of bound polyanions on the protein structure. The enzymatic activity of GAPDH and size of the complexes were measured. The aggregation level was determined from the turbidity.
  
  
  RESULTS
  Highly polymerized PP chains were able to suppress the aggregation completely, but at significantly higher concentrations as compared with poly(styrenesulfonate) (PSS) or dextran sulfate chains of the same degree of polymerization. The effect of PP on the enzyme structure and activity was much gentler as opposed to the binding of dextran sulfate or, especially, PSS that denatured GAPDH molecules with the highest efficacy caused by short PSS chains. These findings agreed well with the enhanced affinity of polysulfoanions to GAPDH.
  
  
  CONCLUSIONS
  The revealed trends might help to illuminate the mechanism of control of proteins functionalities by insertion of charged groups of different nature through posttranslational modifications.
  
  
  CONCLUSIONS
  Practical implementation of the results could be the use of PP chains as promising tools to suppress the proteins aggregation without noticeable loss in the enzymatic activity.
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Moscow, Russia. psemenyuk@belozersky.msu.ru
authors.forename: Pavel I
authors.initials: PI
authors.lastname: Semenyuk
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Muronetz
authors.forename: Thomas
authors.initials: T
authors.lastname: Haertlé
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Izumrudov
mesh_terms: D000838:Anions; D002151:Calorimetry / Q000379:methods; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000737:chemistry*; D010316:Particle Size; D011122:Polyphosphates / Q000737:chemistry*; D011487:Protein Conformation; D013696:Temperature
chemical_list: D000838:Anions; D011122:Polyphosphates; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases
keywords: DS(x); DSC; Dextran sulfate; GAPDH; PP(x); PSS(x); Poly(styrenesulfonate); Polyanions; Polyphosphate; Protein aggregation; Protein sulfation; dextran sulfate containing x charged groups per molecule; differential scanning calorimetry; glyceraldehyde-3-phosphate dehydrogenase; poly(phosphate) with the degree of polymerization x; poly(styrenesulfonate) with the degree of polymerization x